4 inch MAF

Hello guys, I wanna make a 4 inch side intake, and I was wondering if the maf sensor will work without a honeycomb in front of it, or it will affect the idle? The car will be mapped after that to suit the bigger housing. Has anyone done this mode? Any advices?

FC Performance have a 4 inch MAF conversion so drop him a PM mate

Why don't you ditch MAF and use MAP? That is if you are using a stand alone ecu.

I'm on stock ecu!

Contact Flea on here or email him.

http://www.fcperformance.co.uk/

honeycomb before sensor has function - it make the airflow more even (velocity profile) across the pipe diameter, so you have more precise data from sensor... without it you get the data somehow distorted based on the shape of current velocity profile.. but it will somehow work.

What is standard maf size

What does increasing the diameter do and would you need to modify anything via remap or using avcr?

Standard maf size is 76mm and it maxes out at around 400hp. If you increase the size of the housing you need to remap the ecu.

I tried to solve bigger MAF properly rescaled in bosch ecu. But this 2.10.4 ecu has some limiter and when new maf reads higher hex value than maximum value from oem calibration curve, its throw MAF DTC error. I bandaid it by disable this DTC message, but still have problems with stability around idle(very big injectors, ethanol fuel...)
Only way without DTC error is to not touch scale curve, just roughtly adjust maf axis to suit real condition. But still will be weird condition for example decel fuel cut will not be engaged correctly, ect.
So i decided to convert to "normal" standalone ecu.

Btw stock maf maxes at cca 300bhp and my tested 3.5" housing(bmw OEM maf housing incl. honey mesh) maxes at cca 400bhp. Confirmed by measuring, not repeating info from internet;)

You can definitely get 400 bhp with the stock MAF and housing. I've done this myself.

Also there are two 10x1 MAF limit tables, one at CE3F and one at CE55. These allow you to raise the MAF limit - or you can just disable that nonsense by filling them with 255s

Im not talk about physical restriction, i was about voltage signal to ecu. I done 400bhp on stock maf also, but there is start to be lack of resolution for multiple boost levels or parthrottle accel at high rpm.

Two limiters tables, and others limiters i try to find not have influence on problem i noted, i think its must be somewhere some single value limiter of max kg/h value (MLMAX called in newer motronics) or something like that. I tested, last value on stock MAF curve is 1C95 hex at 5volt, which calculate is cca 914kg/h, i rescaled curve for 3.5" housing to read up to 1250kg/h at 5volt and every time maf signal passed 1C95 (which was in my curve little after 4volt) i recieved MAF error (incl.Injector light on dash). If you have different experience let us know.